Mold for battery grid plates



March 19, 1940. A. D. LUND MOLD FOR BATTERY GRID PLATES Filed Dec. 23, 19157- 2 Sheets-Sheet l IIZIIAI l i l l i I l 1| March 19, 19419.l

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177' TOR/YE Y Patented Mar. 19, 1940 PATENT oFFlcE MOLD FUR BATTERY GRID PLATES Arthur D. Lund, Minneapolis, Minn., assignor to Solar Corporation, Milwaukee, Wis., a corporation of Delaware Application December 23, 1937, Serial No. 181.298

4 Claims.

This invention relates to improvements in molding devices for casting machines.

The molding device as herein referred to is of the type employed in grid casting machinery in A which storage battery grids are cast. For thisv purpose the device is made up of two complementary molds or dies having in their meeting faces the intaglio or matrix surfaces which, when filled with the molten metal, will form the lo battery grid to the desired shape and formation. The molds of course are movable toward and away from one another in `order to allow the removal of the formed grid after it has hardened between the molds. Hitherto, in devices of this ll kind, dimculty has been experienced in so feeding the molten metal between the molds that it will lill the entire matrix surface and which action of course is necessary in`order to mold perfect and complete grids. This difficulty has aris- 30 en fortwo reasons, the iirst being that the feedingv method itself has been unsatisfactory and the second being that no satisfactory means has been provided to enable the air in the space formed by the matrix surfaces to exhaust prop- '35 erly and completely. Diiculty hasv also been experienced due to the rapid cooling and contraction of the thin grids causing fracture and breaks around their margins.

With the above vfacts in mind it is the primary $0 object of my invention to provide a molding device for this purpose in which the molten metal metal thus will cool more slowly than the thin grid itself and asthe metal in the grid hardens and contracts this still molten metalmay expand to compensate for the contraction of the metal in the matrix surfaces. This action of course greatly facilitates the formation of perfect grids and entails no diiliculty in expense since the wide grid and melted for use again.V Another object is to provide a molding device in which adequate, and properly located, means is provided to allow the air to rapidly and completely exhaust from I l the mold cavities as the molten metal enters.

bar thus formed may be trimmed from the g,

Still a further object is to provide a molding device .of this kind in which a plurality of grids may be cast in one operationand in one large plate to be subsequently trimmed to size and in which means are provided for cjectng the plates from the molds and for cooling both the plates and the molds to aid in hardening the plates and to prevent warping of the molds. These and still other more specific objects of my invention will be made apparent in the course of the following detailed specification, reference being had to the accompanying drawings, wherein;

Figure Il isa face or inside elevation of one of the molds or dies constructed in accordance with my invention, fragments being broken out` to better disclose interior construction.

Figure 2 is a cross section along the line 2-2 in Figure 1, butv showing both mold plates in their operative positions Figure 3 is an edge or end view of the molds with parts shown in cross section to better illustrate the construction.

Referring now with more particularity to the drawings the reference character A designates the movable mold and B the stationary mold, the two of which constitute the molding device as provided in this invention. Machines for operating these molds, filling them with the molten metal, circulating the cooling uid through the molds and otherwise performing the casting operation are so well known in the art as to require no description herein. The terms movable and stationary as employed herein are further understood to be purely relative terms and used solely for convenience in description since either or both of the molds may be movable and reciprocated by the machine. 'I'hus features which are herein described as for the fixed mold, might as well be employed in a movable mold and vice versa. As herein disclosed, however, the mold A' is secured to the machine by any-well known means (not shown) while the mold B is arranged to be reciprocated by the machine-by a conventional actuating means (also not shown) in such manner that the mold faces will be alternately moved together and apart as the machine operates. 'I'his action is continuous so long as the machine is in operation and it may here be noted, to enable a better understanding of the need and function of my invention in all its details, that the 'entire Voperation of filling the mold, hardening the grid and discharging it from the molds requires but ajsmall fraction of a minute to complete. The molds Ior dies themselves take the form of blocks of suitable metal such as cast iron properly chilled and annealed and in accordance with usual practice, the meeting or adjoining working faces of the molds are provided with the complementary intaglio or matrix surfaces designated generally at 5 and 6 spaced apart and spectively of the completed grid. The surrounding channels in the mold faces, designated at 1, form the outside frames for the completed grids and lateral extensions 8 at the upper ends of the outermost channels form tabs by which the grids are subsequently secured to thebattery terminals.

I'here are also formed substantially L-shaped and reversely turned feeding channels 9 and III adjacent each end o'f each mold face and these comprise the vertical portions IIwhich extend downwardly alongside the ends of the grid forming matrices 5 and 6 and the horizontally and inwardly turned distributing channels I2 spaced from the lower margins of the matrix surfaces. Intervening ribs or uncut portions I3 and I4 of the mold faces isolate these channels from the matrix surfaces as clearly shown. However, at the bottom and in the ribs Il, there are formed a series of narrow perforations or inlet grooves Y ends finally turn upwardly intermediate the surfaces 5 and 8 to form a channel I1 which will provide a medial connecting rib for the cast plate. The vertical channels II also taper in width from their upper to their lower ends and the purpose of this gradual restriction of the channels toward their discharge ends is to concentrate the metal as it ls gradually fed to the matrix surfaces and ensure that it will be fed evenly across the full width of the bottom of these surfaces. In 'this connection it is noted that the channels are so formed that there are provided. overhanging or projecting shoulders Il and I9 before each series of grooves I5 and I6 and toward the inlet ends of the channels so that the greater part of the metal will be deflected past the adjacent grooves and on toward subsequent grooveswhich might otherwise not receive their full share of the metal. 'I'his feature assumes greater importance when it is considered that the filling of the matrix surfaces must not only be complete and even over their entire expanse but must be practically instantaneous in point of time.

Formed along the upper horizontal edge of the entire matrix surfacelin each plate is an elongated narrow groove or chamber 2|Iwhich communicates along its lower margin with the matrix surfaces to thereby become filled with the metal arising from these surfaces but this groove is cut substantially deeper into the mold face than are the matrix surfaces and conducting channels. As a result there is formed a relatively thick bar or rib across the upper edge of the cast plate and vthe inner face of each mold A and B is evenly cut away between the margins 2| to a depth of about ten one-thousandths of ,an inch so that when the molds move together there is formed a wide clearance, indicated at 22 in Figure 2, which opens upwardly between the molds and communicates with the various cavities therein.

In the use and operation of the molds as so far described, the molten metal is poured into the upper ends of the channels 9 and I9 when the molds are pressed together and the metal then flows rapidly downward through these channelsv and illls the matrix surfaces 5 and 9 as well as all the surrounding channels, 1, I1 and 2l. 'Ihis filling action is evenly distributed by the novel arrangement of the series of grooves I5 along the lower edge of the matrix surfaces supplemented by the relatively small number of grooves at their upper and outer corners. 'I'he filling action is further facilitated by the restriction of the filling channels toward their discharge ends and by the overhanging shoulders Il and I9 as described hereinbefore. All these features contributeto the final result by which the metal rises evenly up through the entire area of the matrices and other cavities and fills them completely. As the metal enters it must of course expel all the air in the various cavities and this is greatly facilitated by the location of the clearance space 22 directly opposite the point at which the metal enters in the greatest quantity. This arrangement prevents the trapping of any air in any part of the cavities and the resultant formation of air pockets in the nished grids as now often occurs. In this connection it is noted that the clearance space 22 opens .into tbemold cavities along their entire widthvor length and with no projecting corners whatever due to the peculiar formation of the margins 2| as indicated.

As the metal in the filled cavities hardens it naturally contracts slightly and hitherto this has `sometimes resulted in fracturing or breaking the relatively thin wires formed by the vertically extended grooves in the matrices. This of course ruins the grids for use and results in considerable waste. In accordance with my invention, however, the relatively deep grooves 2|I along the upper margin of the matrix surfaces forms a relatively thick mass of metal as it enters the grooves and this metal of course will cool slower than the grids themselves, due to its greater mass.

Thus as the grids cool and contract this still molten metal in the grooves 2l may move downwardly and compensate for this shrinkage and so prevent the wire from breaking. The amount of this shrinkage is of course relatively small but nevertheless it has been found to cause the breakage described. Likewise it has been found that the formation of this relatively great mass of metal at the upper margins of the grids compensates for this shrinkage to the extent that the grids are perfectly formed.

For the purpose of properly aligning the cast plates in the trimming machine v(not shown) the plates may be provided with pilot openings by means of the core pins 23 which are seated in recesses formed in the movable mold B and terminate in tapered ends which are located in the lateral extensions 24 of the channels II. These extensions of course become filled with the molten metal forming extended ears at the ends of the plates and the tapered ends of the pins 23 form openings in these ears which may subsequently serve to engage pilot pins in the trimming machine to properly locate the plate therein.

As each plate is cast and hardenedit is necessary to remove it from the mold and this is accomplished automatically as the movable mold B moves back from the mold A so that the c'ast plate drops downwardly from between the molds. For this purpose the cast plate is rst causedto adhere to the movable mold B until it clears the vmold A by means of follower pins 25 which are slidably mounted in the mold A and are normally urged by the coil springs, 26, outwardly from the working face of the mold. In casting position and when the molds are pressed together these pins 25 rest against the pins 23 but as the moldsA move apart the pins 25, being larger than the pilot openings formed by the pins 23, engage the plate and `move outwardly to press the plate against the mold B. This action is limited by the shoulders 21 on the follower pins but ensures that the plate will be substantially clear of the mold A when it is released from the mold B as will be evident.

For the purpose of loosening the cast plate from the mold B after it has cleared the mold A a plurality of kick-out units as indicated at C are provided. 'I'hese units each employ a pin 28 slidably mounted through the mold B to engage a portion of the plate cast therein and spring set by the spring 29 to horizontally just clear the plate. The outer end of each pin is exposed through the end of .the mounting shown and as the mold B moves back away from the mold A eachpin will strike an abutment D on the casting machine causing the pins to move axially and eject the cast plate so that it drops down between the molds. 'I'he kick-out units C are of course suitably located over the area of the cast plate to discharge it evenly from the mold.

In order to facilitate the rapid hardening of the metal after it fills the molds as well as to prevent distortion or warping of the molds themselves from the heat of the metal I provide the cooling system now to be described. Since the cooling system for each mold is exactly the same only one will be described in detail herein.

A manifold 39 is secured by bolts 3l along the lower edge of the mold and is cored outto form the inlet, ,chamber 32 and outlet chamber 33,

each isolated from the other by the intervening Awall 3l, but each having openings in the edge adjacent to the mold. An outlet connection 35 is formed for the chamber l32 and an outlet conwith the filling channels Il and communicate with the outlet chamber 33. The upper ends of each set of ilues are joined by ducts I9 horizontally extended abovethe vmatrix surfaces 'and having further upwardly extended branches 4| which lead to the iiues 39.

both the grid plates as they are cast and upon the molds themselves. While it might seem that the water should enter through the ues 39, due to the coolest water being needed at these hottest parts of the molds, it has been found that the greater volume of water carried by these ues 39 as relative to the volume handled by the inlet flues 31 and 38, more than oilsets the fact that the water is warmest in the discharge ilues. As a result the cooling is substantially even over the entire molds. 'Ihe movable mold B will of course be provided with flexible connections (not shown) to its cooling system so that this system will continue to function as themold reciprocates.

It may be noted that the movable mold B carrises a pilot or dowel 42 which engages in socket members 43 in-the xed mold A to guide the molds into proper register and relation as they move together.

1. A casting mold having a matrix surface and having a channel formed inwardly along one side of the matrix surface, the said mold also having metal inlet grooves spaced along the channel and connecting the vsaid channel and matrix surface -wherebymolten metal may be'owed' inwardly along said channel and into the matrix surface,

- and a marginal portion of the channel being projected into the path of the flowing metal to divert the greater part of the metal past the inlet grooves nearest the outer end of the channel.

2. A casting mold having a substantially rectangular matrix surface, metal feeding means around the lower and outer sides of the matrix surface and spacedtherefrom, the said mold hav-pl ing a series of grooves along the entire lower side of the matrix surface for feeding molten metal from the feeding means to the matrix surface, and the said mold also having a. relatively fewer number of grooves at the upper corner portions of the matrix surface for feeding metal into the said surface at these points.

3. A casting mold having a substantially rectangular matrix surface, the said mold also having metal inlet channels extending along opposite vertical edges of the matrix surface and turned inwardly along the lower margin of said surface for feeding molten metal downwardly and inwardly around the matrix surface, feeding means connecting the lower inwardly turned portions ofV the channels to the matrix surface for conducting molten metal in relatively large quantities into the said, surface, andv feeding means at the upper lateral corners of the matrix surface for conducting lesser quantities of metal from the channels into the matrix surface.

4.. A casting mold having a substantially rectangular matrix surface, the said mold also having metal inlet channels extending along opposite connecting the lower inwardly turned portions of the channels to the matrixsurface for conducting molten metal in 'relatively large quantities into the said surface, feeding means at the upper lateral corners of the matrix surface for conducting lesser quantities 4of metal from the 

